3
modules of the protection unit and a yellow
indication I
hr
> is lit on the front plate. The
blocking function may be set to be operative
only during switching inrush current situations
by setting switch 8 of switchgroup SG1 in
position 0. When the currents on both sides of
the protected object go below 10 % of the relay
rated current for about 100 ms, the blocking is
enabled and the relay starts waiting for a
switching inrush situation. The switching inrush
current event is regarded to have stopped
when both currents exceed 20 % of the relay
rated current. If switch SG1/8 = 1, the blocking
is always permitted.
A high-set instantaneous stage I
d
>> operates
in parallel with the differential current stage.
The starting current of the high-set stage can
be set over the range 20…30 x I
n
in steps of I
n
.
When the bias current I
b
falls below 33 % of the
differential current I
d
, the setting value of the
high-set stage is automatically halved because
in a situation like this a fault exists inside the
protected range. At the same time the blockings
are restrained.
Note! The blocking signals BS IN and BS OUT
can block the differential current stage I
d
> only.
The operation of the high-set stage I
d
>> is not
blocked.
By means of switch SG1/7 the tripping signal
TS can be given a so called latching feature.
When latched the tripping signal remains alert,
though the reason for tripping disappears. The
tripping signal is acknowledged by simul-
taneously pushing the STEP and RESET push-
buttons.
The signal abbreviations used in the connection
and block diagrams are derived from the English
names of the signals. The following abbrevi-
ations have been used in these instructions.
Load current I1 of the HV side I
1
Load current I2 of the LV side I
2
Differential current I
d
Stabilizing current I
b
Relay rated current I
n
SignaI
abbreviations
2nd harmonic current I
2f
Harmonic restraint current I
hr
Trip signal TS
Blocking signal BS
Internal relay fault IRF
Enable ENA
Receiver channel Rx
Transmitter channel Tx
Yellow operation indicator Y
Red operation indicator R
B
To Next Page
Loading...
